Automatically generated parts cannot be edited and other issues

There seem to be some problems with the part generating feature. First, the handbook page https://musescore.org/en/handbook/3/parts has an inconsistency with version 3. It says that to create all parts it is necessary to click the "New All" button, but this button doesn't exist in version 3. There is a button at the same position called "Generate". Clicking it the parts are generated. However, they cannot be edited.
Even if one can change the name of the part, this change doesn't reflect on the corrsponding tab in the editor, nor on the name of the part. The later can be changed manually but the tab keeps the old name.
Another problem is that one cannot add any new instrument to the part (they are grayed out). It would be interesting to start from an existing part to create a custom part, instead of creating a new one from scratch, particularly because probably the new part supersedes the old one, so one must finally erase it.
Finally, if one ceates a new part, when clicking Generate, all the parts are generated again (duplicating the old ones), so the extra parts have to be manually deleted, which is also dangerous in case one has already made layout changes since the names are the same. It would be better if the list of already existing parts didn't mix with the custom part to be created. The button "All New" was more clear, since when reading "Generate" the user tends to think that is necessary to click that button to generate any part, while it is valid only to generate automatically all parts